For carrying out series experiments on solid nutrient substrates, the use of agar plates is customary. In such cases, the microorganisms are applied as individual seeds to the solid culture layer and incubated to the respective reaction temperature. The material transport (substrate from the solid cultivation layer and oxygen from the gas phase) is effected purely diffusively.
The classical apparatus for the cultivation of microorganisms in series experiments is the shaker flask apparatus. Such apparatus allows reaction volumes from several milliliters to 1000 milliliters to be used to carry out many experiments in parallel with the aid of the shaker incubator. The energy input for dispersing the liquid phase (medium and microorganisms) is effected via a circular movement of all of the reaction vessels which are arranged on a platform. The oxygen input is effected only, in such cases, via a surface gasification. The material transport in the liquid phase is effected convectively. For miniaturization of this technique (so that still more experiments can be carried out in parallel) it has been proposed to use microtiter plates as reaction vessels. Use of this technique has been hindered by special problems in evaporation because of an unsatisfactory surface to volume ratio.
A technique which is extremely expensive from the apparatus point of view for carrying out series experiments with the microorganisms is the parallel use of laboratory fermenters. For this purpose apparatus must be provided which enables parallel processing of up to six fermentations with a single device. The energy input is here effected by standard stirring elements. Via a gasification device, volume gasification is possible.